• Journal of radiological science and technology
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• v.32 no.2
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• pp.153-160
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• 2009

In this study, we investigated utility of ultrasonography for urinary tract infections of infants. The results of the research is as follows : 1. The number of infants under one year old was 100 out of 122 infants who were diagnosed as a unitary infection. The ratio of males to females was 1.7 : 1. Seventy-seven infants who underwent three kinds of radiologic examinations such as kidney sonography (51%), $^{99m}TC$ DMSA-scan (42%), and VCUG (22%). 2. In comparison of correlation between kidney sonography and VCUG, the sensitivity of kidney sonography was 82% while the specificity of kidney sonography was 58%. In comparison of correlation between kidney sonography and $^{99m}TC$ DMSA-scan, the sensitivity of kidney sonography was 66% while the specificity of kidney sonography was 67%. 3. Utility of kidney sonography showed the highest efficiency when we considered pain, discomfort, a sense of shame, psychological stress when infants may undergo at the examination, side-effect of a contrast agent after the examination, and complication of exposure to radiation.

• Progress in Medical Physics
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• v.20 no.3
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• pp.159-166
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• 2009

Obviously, the administration of the prescribed amount of activity to the patient requires proper operation of the dose calibrator, which shall be verified by implementing the required quality control on the instrument. This investigation examined the accuracy and precision of dose calibrator activity measurement of the radiopharmaceutical F-18 FDG. To investigate the status of the nuclear medicine centers in Korea for the performance of dose calibrators, 10 centers providing PET/CT system services in Korea were inspected in 2008. We measured accuracy and precision in 10 equipments in consideration of PET/CT model, installation area, and installation time. According to the results of comparative analysis of 10 dose calibrators used to measure radioactivity of F-18 FDG, accuracy was -5.00~4.50% and precision was 0.05~0.45%, satisfying the international standards, which are accuracy ${\pm}$10% and precision ${\pm}$5%. This study demonstrated that, for accurate measurements, no adjustment is necessary for a dose calibrator setting when measuring different dose calibrators of F-18 FDG activity prescriptions.

• Journal of radiological science and technology
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• v.27 no.3
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• pp.25-29
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• 2004

Among the digital radiography systems, the computed radiography Image Plate Detector System is most frequently being used for the general radiography and also this system commonly diffracts the x-ray images since it is the system that is influenced by the light diffusion from the fluorescent substances. In this study, by using the X-ray Generator, a comparative analysis has been made between 2 different models of computer radiography image plate investigate each model's resolution and sharpness through the modulation transfer function(MTF) measurement. For the analysis, two image plates for general radiography one Fuji ST-VN model(more than 3years old) and one Fuji ST-VL model(less than 2years old) that are currently being used in "Hospital A" were sampled for the MTF measurement here. As the experimental method for this study, the resolution chart method has been carried out by using X-ray generator. Also all the experimental data were printed out by laser printer and measured by microdensitometer. As the results of the experiment carried out in this study, some differences have been found between the two different IP models and Fuji ST-VL has shown its excellence in both of the resolution and the sharpness fields.

• Journal of radiological science and technology
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• v.9 no.1
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• pp.51-63
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• 1986

We got the following results from the 324 radiologic technologists as we surveyed their working condition by using the questionaire, who were working in the medical institutions (general hospitals and doctor's clinics) situated in the area of Seoul city, Kyung ki-do and Chung-chong-do since June to December 1985. 1. Their daily average working time was almost within 10 hours (in 93.9% of general hospitals, 66.1% of clinics). 2. About the numbers of holidays, 85.5% of general hospitals have one holiday per week,41.3% of clinics have one holiday per week or 38.5% of clinics have one holiday per two weeks. 3. Duty appointment of radiologic technologists in the department of radiology is taking charge of each part after serving for a certain part for some period (42.8%), taking charge of the special part continually or by turns in other working parts (35.3%). On the other hand in the clinics they took charge of all parts continually (53.2%) or by turns with their own situations. (30.3%). 4. Their daily working amount is too much in 51.6% of general hospitals or 45.8% of clinics. 5. They answered it was hard in 81.4% of general hospitals or 43.1% of clinics about the degree of difficulty of their work. 6. Their monthly salary is higher in the clinics than in the general hospitals and higher in Seoul area than in Kyung-ki or Chung-chong area. 7. Their yearly bonus .ate is 400%-600% (69.2%) in almost general hospitals, 100%-300% (57.8%) in th. clinics. 8. Danger allowance is paid with the monthly salary in 62.8% of the general hospitals or 19.2% of clinics and license allowance is paid in 44.7% of general hospitals or in 12.8% of clinics. 9. Their initial salary (except bonus) is about 200,000 won (in 76.8% of general hospitals, in 67.8% of clinics). 10. Their salary is raised regulary every year in 52.6% of general hospitals, but it is irregulary in 73.4% of clinics. 11. Promotion system is managed in 48.4% of the general hospitals or in 14.7% of clinics. 12. Retirement allowance is assured in 96.9% of the general hospitals or in 63.3% of clinics. 13. Main cause of their retirement is moving to more paid hospitals, better hospitals in working condition or facilities, moving to another cities, to the hospitals with more opportunities of promotion or choosing other jobs etc. 14. Human relationship with doctors, nurses or co-worker technologists as a member of medical team appeared almost intimate and good.

• Journal of radiological science and technology
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• v.30 no.3
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• pp.237-243
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• 2007

Phantoms are very necessary for quality assurance of radio nuclides imaging systems to maintain standards and to ensure reproducibility of test. General quality assurance and instrument quality control are essential in every hospital. The human tissue equivalent materials are aluminum, areryl, water and epoxy..etc. It is very important to select optimum equivalant materials for a phantoms in QC. Especially, paraffin is very similar with human soft tissue in X or Gamma-ray physical characteristics and easy to buy with economically. We made a paraffin thyroid phantom and compare with thyroid areryl phantom, also used commercially in practice. Two small size cold spots(3 and 6 mm diameter) and a hot spot(3 mm diameter) embeded in paraffin phantom. And imaged with $^{99m}TcO_4$ by camera for analysis about spatial resolution and noise at the hot and cold spots. We got some results as below : 1. No difference in counting rate and noise between both arcryl and paraffin thyroid phantoms. 2. The best spatial resolution can be seen 6 cm distance between pinhole collimator and thyroid phantoms(arcryl and paraffin). 3. More optimal spatial resolution could acquired in paraffin thyroid phantom. Paraffin is very similar with human soft tissue in atomic number, density and relative absorbtion function, and can be shaped easily what we wanted. So we can recommendation paraffin as quality assurance phantom because its usefulness, economical benefit and purchasability.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.83-90
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• 2011

To prospectively determine the diagnostic performance a combination of standard bolus-chase magnetic resonance (MR) angiography and MR angiography with time-resolved imaging of contrast kinetics (TRICKS) for depicting severity of the head and neck vascular diseases. Over a period of two months, A total of 100 patients(average ages : $50{\pm}8$, male : 60, female : 40) with head and neck vascular diseases were performed on the GE excite 3.0 T units with 8-channel head coil and 4-channel NV coil. Imaging parameters for a typical study were as follow: SBC(TR/ TE/ FA/ SliceThicken./ Slab/ Freq./ FOV/ BW/Scan Time) = 5.4/ min/ 30/ 2/ zip2/ 70/ $224{\times}448$/ 30/ 62.50/ 28, TRICKS(TR/ TE/ FA/ Slice Thicken/Slab/ Freq./ FOV/ BW/ Temp Res./ Scan Time = 3.6/ min/ 25/ 4/ 30/ $160{\pm}384$, zip512/ 30/ 100/ 1 to 1.5/ 23). The analysis of all MR images, which have respect-ively classified two techniques into some diseases. The results of the former were divided into two groups(SBC, TRICKS)with 4 grading of two reader, respectively. Wilcoxon signed rank test was used to determine if a significant difference between imaging techniques existed(p < 0.05). In 33 of 100 patients, arterio-venous malformation was 11% at TRICKS, subclavian vein stenosis : 8%, fistular sinus : 4%, jugular vein stenosis:6%, Middle Cerebral Artery bypass surgery : 4%, p < 0.05). The rest of 67 patients were considered as the results of SBC(14% in the basilar artery stenosis, carotid stenosis : 16%, vertebral stenosis : 17%, central neuro-cytoma : 5%, meningioma : 5%, Not appliable : 10%, p < 0.05). Sensitivity and specificity of TRICKS MR angiography in SVS, FS, JVS, MCABS were improved compared with those at standard MR angiography. In SBS MR angiography which were improved in BAS, CS, VS, CN, Meningioma. In conclusion, TRICKS MR angiography of the SVS, FS, JVS, MCABS is superior to standard MR angiography regarding the number of diagnostic grading. The SBS MR angiography were improved in BAS, CS, VS, CN, Meningioma. and assessment of the degree of luminal narrowing on both TRICKS and SBS.

• Journal of Biomedical Engineering Research
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• v.29 no.1
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• pp.66-72
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• 2008

The major risk associated with the use of automated power injectors is the well known complication of contrast material extravasation at the injection site. Automated injection of computed tomography (CT) contrast media can produce the compartment syndrome. The purpose of this study was to assess the ability of this device during clinically important episodes of extravasation. The extravasation detection accessory (EDA) system was composed of a strain gage, an amplifier and a computer based system. A strain gage pliable adhesive patch was applied to the skin aver the intravenous catheter and the catheter was connected to the power injector with a cable to monitor the resolution data. If the programmed monitoring, which was developed with MS Visual C++, at the extravasation occurred, then the injection was interrupted the auto injector. CT was used to demonstrate the clinically important extravasation. This study was a prospective, observational study in which the EDA system was used to monitor the automated mechanical injection of contrast material in 7 dogs. There were two true-positive cases (range of extravasation volumes: $18{\sim}22ml$), twenty three true-negative cases, three false-positive cases and no false-negative cases. The EDA system had a sensitivity of 100% and a specificity of 88% for the detection of clinically important extravasation. The EDA system had good sensitivity for the detection of clinically important extravasation and the EDA system has the clinical potential for the early detection of extravasation of the contrast medium that is administered with power injectors. The EDA system is easy to use safe and accurate for the monitoring extravasation of the intravenous injections, and this system may prove especially useful in CT applications.

• Journal of radiological science and technology
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• v.21 no.1
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• pp.52-58
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• 1998

We can and must improve the diagnostic images using available knowledge and technology. At the same time we must strive to reduce the patient's integral and entrance radiation dose. Reducing the integral dose to the patient during the radiologic procedure is a primary concern of the patient, especially the pediatric patient, the radiologist and the technologist. A 100cm focal film distance generally is used for most over-table radiography. The early x-ray tubes and screen film combinations required long exposures, which often resulted in motion artifacts. But nowaday, we have the generators and x-ray tubes that can deliver the energy necessary in a very short time and the receptors that can record the information just as rapidly. And, we performed this studies to evaluate the patient exposure dose and the image quality by increasing focal film distance in diagnostic radiography. There are many factors which affected to exposure factor, but we studied to verify of FFD increase, only. Effect of increasing the focal film distance to a 140 cm distance was tested as follows; 1. The focal film distances were set at 100, 120, and 140cm. 2. A 18cm acryl(tissue equivalent) phantom was placed on the table top. 3. An Capintec 192 electrometer with PM 05 ion chamber was placed at the entrance surface of the phantom, and exposure were made at each focal film distances. 4. The procedure was repeated in the same manner as above except the ion chamber was placed beneath the phantom at the film plane. 5. Exit exposure were normalize to 8mR for each portions of the experiment. Based on the success of the empirical measurements, a detailed mathematical analysis of the dose reduction was performed using the percent depth dose data. The results of this study can be summerized as followings ; 1) Increasing FFD from 100 cm to 140 cm, we would create a situation that would have a significant effect on the overall quality of radiograph and achive the 17.42% reduction of entrance dose and the 18.95% reduction of integral dose that the patient receives. 2) Thickness of Al step wedge for equal film density increased with the long distance. 3) Increasing FFD, Magnification of image was lowered. 4) Resolution of image also increased with the FFD. As the results described above, we strongly recommend using the long FFD to provide better information for our patients and profession in abdomen radiographic studies.

• Journal of radiological science and technology
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• v.29 no.1
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• pp.21-28
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• 2006

I made inquires about mammographic equipments and circumstances of mammography rooms in the 64 medical facilities in areas of Seoul and Kyong Gi Do. Moreover I had experments about exposure dose with patients and radiologic technologists. so there is the data indicated follows. 1. There are inclined to improve in quality and function of mammographic equipments, it has been proven that s/f system exchanged to DR system. 2. It is certain that the number of examinations are becoming increasingly significant. 3. The Space Scattered Dose of mammography rooms are much more larger than portable equipments. 4. I worry about the affection of expose dose about Space Scattered Dose of mammography room. 5. There is need of study how to cope with the situation about increasing exposure dose of radiologic technologists in small space and numeruous number of examinations.

• Journal of radiological science and technology
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• v.28 no.3
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• pp.235-239
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• 2005

The bone mineral density built in adolescence and college term is formed to the highest level between 25 years old and 35 years old and the formed bone mineral density is decreasing in the middle years and senescence. Decrease of the bone mineral density causes Osteopenia and an increase of dangerousness of a bone fracture which become social health problems. This research is to give guidance for the right living style by surveying the relation between the bone mineral density and college students' life. The result is like below. First of all, most objects of the research were insufficient of quantity of motion and the diet they have was consisted of instant food. It was far from the right living habit and exercise and the bone mineral density was also low. Second of all, male students showed more osteopenia than female students in this research and the smokers' bone mineral density was lower than nonsmokers, which proved that smoking in adolescence was related to the bone mineral density. Finally, the opportunistic eating and living style and the excessive diet and unequal caloric intake caused by the notion of preference for a slim person are considered to be the main reasons for the decrease of the bone mineral density.